Charts - Showing/Making boxes on charts (or graphs)

[Tomo8281]

Right guys, another lovely question from me :)!

I have a signal (its an ECG signal but it doesn't really matter in this part of the project), that I want to send into a graph/chart, and pause it. This is going to be my 'analysis mode' so that the people watching the graph can print out it or look at it. Hopefully this will be a chart/graph with a background of boxes with the axis.. Its hard to explain so here is a picture:

 

So the chart needs to have little boxes in the background. 5boxes by 5boxes is considered a LARGE box. This contains 25 small boxes of course, this large box is 0.2seconds across and 0.5mV up. Each small box is 0.04seconds across.

As you can properly see its a bit hard to understand if you don't have everything in front of you. This is what the proper ECG systems use to print out the data and have a analysis look at (he compares the boxes). 

Can anyone help me with this, I just need ideas to get started! Its a bit of an odd request and I really don't expect anyone to understand, its just a shot in the dark :)!

Thanks a bunch,

Tom.

[mikeporter]

The boxes you describe are called a grid, and the good news is one comes free of charge with each and every graph! In fact, they are there by default. You actually have to do some work to turn them off! Just set it and forget it!

Ron Popeil I mean, Mike...

[Tomo8281]

Really? Damn never knew that! Ill have a look later today when im in the lab :)!

Also one more thing. About the 'freezing' of the graph, for some reason mine doesnt like it and just ignores it. I dont have the VI with me. But is there any way to freeze a chart while still holding the last values that passed through it? So it just stops, then when you un freeze it it updates and continues to show the signal?

[tst]

Just stop pushing data into the indicator (e.g. by placing a case structure around it). If you want to keep logging the data at the same time, then you're better off switching to a graph. I like using the XY graph and have a VI which allows it to maintain a circular buffer, similar to how the chart works. You should be able to find a simple version of it here if you search for "XY chart".

[Tomo8281]

Hmm, well im having a problem with this :x!

 I found a good way from an old project to 'freeze' a graph. Wire up Enable and Reset to a Bool switch and when you want to freeze it, set it to true! This works but not in my VI for some reason the Build XY Graph isnt building my graph correctly :\!

Also why does it say 'Y: 3123 Y: 123' when i probe the wire going to my Analysis 4 chart, shouldnt it be 'Y: 3123 X: 123'? Where has the x axis gone??

Ive attached the VI since this is hard to explain, any help would be super! 

[tst]

I don't use that express VI or the datatypes that you used, so I can't give a qualified answer, but if you open the diagram of the express VI (right click it and select Open Front Panel and then click the convert button) you can look inside the code. The reason you get two Y's is because the person who built the express VI extracted the Y element from two waveforms. You're not getting anything because the X you're wiring is a single value and the VI doesn't maintain history. As I mentioned, you can search the forums for a VI which does this, although it won't work directly with waveforms and dynamic data.

To learn more about LabVIEW, I suggest you try looking at some of these tutorials.

[Tomo8281]

Went through at least 20 pages of the forums containing XY Waveforms or similar items. None seemed to be involved in what im doing which is something so simple i think im an idiot since it doesnt work :(!

Can anyone who does have the XY express vi take a look? Its on the base package i'm sure..

[tst]

I didn't say I don't have the express VI. I said I don't use it and then I explained the problem.

I also said you should search for "xy chart".

[Cory_K]

Heres a pretty simple method to building an XY graph, and also creating a 'Pause' feature on the graph.

* Note, I did not use the Express XY Graph VI either.... I'm not really a fan of express VI's

Look at the attached VI and see if you can follow what is going on.

That could help you figure out how to modify your VI.

Message Edited by Cory K on 03-10-2009 12:01 PM